Single reflector type microphone



Aug. 4, 1936' .o. B. HANSON ET AL v 2,049,586

' SINGLE REFLECTOR TYPE MICROPHONE Filed March 9, 1932 2 Sheets-Sheet l INVENTORS O. B. HANSON BY ROBERT M. ORR IE A oR EY o. B. HANSON ET AL 2,049,586

Aug. 4, l936;-

' SINGLE REFLECTOR TYPE MICROPHONE 2 Sheets-Sheet 2 Filed March 9, 1932 iNVENTORS o.s. HANSON BY R-OBER M. ORRI5 A .OR EY Patented Au'gi 4,:11936 I t I 49,;

UNlTED ,sr-A Es' PATENT OFFICE smcm nnrmcroa ma MICROPHONE Oscar B. Hanson, Westport, Conn and Robert M.

Morris, Milburn, N. 1., assignors to Radio Corporation of America, a corporation of Delaware Application March 9, 1932, Serial No. 597,648

8 Claims.

This invention relates to a, sound reflecting miverberations, loss of the higher frequencies, excrophone and more particularly the type used in traneous sounds, and distortion of tonal qualiradio broadcasting. ties due to selective absorption of the walls, ceil- An object of this invention is to simplify and in fl improve microphones of the sound reflecting type. t In the drawings like reference characters re-' Another object of this invention is to provide f r t similar Darts hw li h s v vi a portable sound refiecting'microphone for pickin which, ing up certain sound waves from a distant point Fig. 1 is a vertical cross section, this section I excluding other surrounding and undesirable being taken on lines l| of Fig. 2;

msound waves. Fig. 2 is a front elevation of the improved re- A-feature of this invention is the novel means flectorf for determining the precise location of desired Fig. 3 is a vertical cross section of an improved sound energy. I modification of a portable reflector type micro- The present invention, it has been found, is phone;

is" more highly efflcient than those heretofore em- 3 elevatmn 01 improved ployed. This is due to the arrangement oi the able reflector microphone; 4 I apparatus whereby the sound waves received are 1 Fig.- 5 is a view of the adjustable microphone reflected in concentrated form upon the microstand with the adjusting means shown in section.

' .phone diaphragm thus causing an'apparent am- The invention of the studio type reflector mipliflcation of the sound wave energy and an incrophone is best illustrated in Figs. 1 and 2, 2o

crease in the effectiveness thereof. When a rewherein .the concave reflector l, which is approxflector is not used the sound waves entering the ime ely 3 feet in diam ter, is mp d of imp phone are scattered and only a portion of nated fabric or any other satisfactory sound rethe available energy is utilized to effect the diaflecting material. It is shaped in accordance with v of t m m g, the curve of a section of a par il The reflector microphone of this invention oprotated about its axis. forming a paraboloid and ,erate's on the principlethat sound arriving at its is also provided with a flattened rim portion.

' surface in a beam parallel to the axis is reflected This reflector is mounted upon a suitable pivto its focal point at which position a microphone otd supporting yoke member 2 which is pivoted is located. Withthe microphone in this position at the center of the large reflector l by means of ,the reflector is highly directional, materially in-f bolts 3 and wing nuts 4. Directly belo the y creasing the amplitude of sound arriving-in the member 2 there is an upright supporting post 5 direction of the reflector axis and effectively atwhich is adjustable for height by means of a tenuating sounds from otherdirections. Removal telescoping post I and a set screw 6, and is rotated v of the microphone from the ,focus and locating in a lower bearing 8 held in position by means 'it at some other point along the axis decreases of a set screw 9 which allows the posts 5 and I the directional characteristic and broadens its to rotate in a slot). The upright posts 5 and angular response. 'l are firmly secured to a stand II by means of Heretofore sound reflectors have been used to a socket l2. A microphone M is supported by demonstrate in a theoretical manner the utility two metallic rings l3 and M which have four 0 of a device of this nature. The construction or round rods l5, -l6, l1 and I8 mounted thereon.

-' these reflectors have in some cases been made These rods are slidably supported by means of of concrete, thus making them massive and cum-- four larger supporting rods I9, 20; 2| and 22 bersome. Hence, they have not been used fo which fasten the microphone and adjustable rodsany prac ical purpose. The reflector about to be to the flattened rim portion of reflecto I. For 45 described herein, is of such design, size and determining the precise location of th desired weight as to be readily portable and adapts itself sound energy there is provided a sighting ball 23 for use outside the broadcasting studio, such as g h i fastened t th microphone by means in a bas b P football stadium, or the like. of a rod 24. Directly in line with the ball 23 With this improved reflector microphone, and there is a small aperture- 25 in the reflector I, 0 more particularly; due to its sound directional and the desired sound waves are picked up by properties, it may be used at distances from the sighting through the aperture 25 and lining up source of sound energy without introducing the the ball 23 with the object of the desired energy complications whichsometimes are obtained with source. a b

the ordinary microphone, namely, increased re- Referring now to Figs. 3 and 4 which are so modifications of an improved microphone particularly adapted for outdoor use, there is shown yoke 21 and thepost 28 are arranged to'provide rotation of the "reflector 26 by means of a slot 32 which is locked in position by means of a set screw 33. The microphone M is mounted upon a.

bracket 34 and is'providedwith a ballfl35 which 5 is supported by means of'a rod 36. Anzapertur'e 31 is provided in the reflector 26 by the operator sighting through the aperture and up the ball 23 with the object of which the desired directive sound pick-up is to be obtained. The microphone M and reflector 26 may be furtheradjusted by a pivot 38, and is clamped in position by means of a clamping member 39. To adjust the focusing distance between the microphone M and the reflector source 25' an adjustable screw thread 40 is provided, the reflector 26 being fas tened to a suitable bracket which is-clamped by means of screws 42 and 43. This-bracket is" guided by means of a support 44 and pins and 46 which are guided in a slot 1 in which amov-' able nut 48 is located. When the proper focal distance is obtained, the members 4| and 44 are locked in final position by means of nut 59 and screw, 50.

Our improved microphone device functions briefly as follows:

'With a microphone located at the focus, it will respond only to sounds arriving in a beam parallel tothe axis as shown by the dotted lines indicated by the arrows A and impinging on the surfaceof the reflector. Other sounds arriving at an angle with respect to the axis as shown by,

the dotted lines and arrows B, will be reflected past the microphone and therefore will be ineffective It is also apparent that this device will be a highly. directional collector of soundenergy. Laboratory measurements have shown it to be highly directional at the high frequencies; and becoming less directional at the lower frequencies. Since the area of the microphone diaphragm is effectively increased, it is apparent that some appreciable magnification of sound energy over that picked up by the microphone alone, will be obtained. Locating the microphone along the axis at positions other'than the focal point, results in broadening the angular response which increases its utility, as its scope is not limited to a. narrow beam which under'normal conditions would be unsuitable for sound energy such as orchestral pick-ups. It is apparent that the reflectors may be constructed of any suitable material which can be formedto follow the shape of the desired curve and which has suitable density, thickness and diameter to reflect the desired band of audio frequencies. Likewise, the size and shape of the reflector may also be changed if it is felt desirable to increase the efilciency or to suit any particular circumstances, as for exam pie, to obtain a responsive beam greater in width than in height such as, for exam le, the shape may be changed to follow the equation of'a curve I other than that of a parabola to secure any other I response other than that obtainable with the refiector so described. I

Although this invention has been described and illustrated, it is apparent that other modifications in its construc ion may be varied in order toobtain the desired results, and yet retaining the supported by a ring-like member, said member secured by a plurality of rods fastened to the rim of said paraboloid. a

2. A directive sound responsive device cometer in the order of three feet, and a curved sec- -.tion of a parabola (g st-1.1:) rotated about its axis forming a paraboloid, a sound responsive microphone adjustably mounted at the focus fundamental principles of this device within the thereof by a plurality of. rods which are slidably 10 prising a concaved sound reflector having a diamll thereof by a plurality of rods which are slidably-l0 supported by two ring-like members, said members secured by a plurality of rods fastened to the rim of said paraboloid. I

3. A directive sound-responsive 'device, commicrophone adiustably mounted at the focus :thereof. by means of a ring-like member which is secured by a plurality of rods, said ring-like ,member secured by a plurality of support rods prising a sound reflector, a sound-responsive ".centrally located on the outer rim of said sound 30 reflector, and a portable stand for supporting said reflector and said responsive element.

4. A directive sound-responsive device, comprising a sound reflector having a sighting aperture, 'a sound-responsive element adjustably located at the substantial focus thereof-by means of two ring-like members which are secured by a plurality of central support rods located on the outer rim of said sound reflector, said soundresponsive element having a plurality of rods 40 sliding through said ring-like members with respect to said sound reflector to receive the desired sound energy. L

5. A directive sound-responsive device; comprising a parabolic sound reflector having a flattened rim portion, a sound-responsive microphone adjustably mounted at the focusthereof by means of four central support-rods located on the outer rim of said reflector, and a plurality of ring-like members having a plurality of apertures in which a plurality of rods are arranged to slidably support said sound-responsive microphone.

6. .A directive sound-responsive device, comprising a parabolic sound reflector having a flattened rim portion, a sound-responsive microphone adjustably mounted atthe focus thereof by means of four central support rods located on the outer rim of said reflector, and a plurality of ring-like members having a plurality cf apertures, a plurality of rods fastened to said micro- 30 phone to slidably support said sound-responsive microphoneby sliding said rods through the apesture in, said ring-like member.

- 7. A directive sounderesponsive device, comprising a parabolic sound reflector having a flattened rim portion, a sound-responsive microphone adjustably mounted at the focus thereof by meansof four central support rods located on the outer rim of said reflector, and two ring-like members centrally located wlth respect to said reflector and having four apertures and four rods fastened to said microphone to slidably support said sound-responsive microphone.

8. A directive sound-responsive device, comprising a parabolic sound reflector having a flattened rim portion, a sound-responsive microphone adjustably mounted at the focus thereof by means 0! four central support rods located on the outer rim of said reflector, and two ring-like 5 members centrally located with respect to said reflector and having four apertures and tour rods fastened to said microphone to slidably support said sound-responsive microphone, and a. portable stand for supporting said reflector and said microphone.

OSCAR B. HANSON. ROBERT M. MORRIS. 

